I make my inserts in Serif PagePlus, but it's the same principle. I use folded ones, print on the right side of the page and, sometimes, put a picture that relates to the front on the left side then I do just what Jan does and put the DST on the inside of the front. As said, it opens with the card then. I have, sometimes, used coloured staples or ribbon to hold it in too. That can look quite nice.